US3898392A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Answer-back assembly for a key telephone system
Assignee: Northrop Grumman Guidance and Electronics Co Inc
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Filing: 1974-02-25
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Granted: 1975-08-05
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Expires: 1994-02-25
Abstract
Abstract The invention relates to a conventional key telephone communication system of the type having a central and a plurality of remote telephone stations interconnected together and further having a paging or announcing channel, as variously termed, provided by a pair of wires that extend between the central station and, in multiple, to each of the remote stations. Each of the remote stations contains an amplifier and loudspeaker assembly to permit an announcement, initiated at the central station, to be made over the loudspeaker of the selected remote station, irrespective of the position of the remote station telephone handset. The improvement includes switch means, a microphone, and a microphone amplifier at each station. In its unoperated position the switch means completes an electrical circuit from the paging channel to the input of the amplifierloudspeaker combination to permit passage therethrough of the incoming announcement, and in its operated position the switch means interrupts said circuit to the amplifier and loudspeaker combination and connects the output of the microphone amplifier to the announcement channel. The improvement allows a received announcement to be answered over the announcement channel directly by simple depression of one switch without the necessity of removing the telephone handset at the remote station or, if the telephone handset is in use over one of the other party lines, without requiring an existing conversation to be placed on ''''hold.
Inventors
- 👤 Joseph Monroe Jackson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 04:58
CPC Classifications
H; H04; H04M; H04M9/00; H04M9/002; H04M9/001
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
583 words
In a key telephone system having a central station, a plurality of remote stations, and means for establishing telephone communications between such stations, the combination therewith including: a first isolation transformer associated with said central station having first and second windings; means coupling said first winding in circuit with said central station; relay means associated with a remote station, said relay means having first, second and third normally open sets of contacts, each of said contact sets operable to the closed position in response to energization of said relay means for completing an electrical path through said contact set; a source of DC power; first and second electrical leads coupled, respectively, between one end and the other end of said second winding of said first transformer and, respectively, to one contact in each of said first and second contact sets to establish two electrically conductive paths therebetween; a third electrical lead connected between said DC source and one contact of said third contact set to establish an electrically conductive path therebetween; a second isolation transformer having a primary winding and a secondary winding, said primary winding having first and second winding ends; a first amplifier having an input and an output and wherein said input is coupled to said secondary winding for receiving AC electrical voltages therefrom; a loudspEaker for converting AC to audio energy having an input; a microphone having an output; a second amplifier having an input and first and second outputs and wherein said input is coupled to said microphone for receiving electrical voltages therefrom; each of said first and second amplifiers having a DC input for receiving DC power; manually depressible spring return type switch means, said switch means having a normal position and an operated position and having a first set of break contacts and a set of transfer contacts, including a break contact, a make contact, and a transfer contact, and further having a spring for restoring said switch means to said normal position; first circuit means connecting said output of said first amplifier, said first set of break contacts and said loudspeaker in electrical series circuit for permitting coupling of electrical voltages between said amplifier and loudspeaker only when said switch means is in the normal position; second circuit means connecting an output of said second amplifier in circuit with said make contact in said set of transfer contacts whereby said output is connected electrically in circuit with said transfer contact only when said switch means is in the operated position; third electrical circuit means connecting the second output terminal of said second amplifier in common with said first end of said primary winding of said second transformer; fourth circuit means connecting the second end of said primary winding to said break contact of said set of transfer contacts whereby an electrical circuit between said transfer contact and said primary is established only when said switch means is in its normal position; fourth electrical lead means connected between the other contact of said first relay contact set and said transfer contact of said switch transfer contact set; fifth electrical lead means connected between the other contact of said second relay contact set and said first end of said primary winding of said second transformer; sixth electrical lead means connected in circuit between the other contact of said third relay contact set and said DC input of each of said first and second amplifiers; and means controlled by said central station for selectively energizing said relay means.
Claim 2
Dependent Claim
583 words
In a key telephone system having a central station, a plurality of remote stations, and means for establishing telephone communications between such stations, the combination therewith including: a first isolation transformer associated with said central station having first and second windings; means coupling said first winding in circuit with said central station; relay means associated with a remote station, said relay means having first, second and third normally open sets of contacts, each of said contact sets operable to the closed position in response to energization of said relay means for completing an electrical path through said contact set; a source of DC power; first and second electrical leads coupled, respectively, between one end and the other end of said second winding of said first transformer and, respectively, to one contact in each of said first and second contact sets to establish two electrically conductive paths therebetween; a third electrical lead connected between said DC source and one contact of said third contact set to establish an electrically conductive path therebetween; a second isolation transformer having a primary winding and a secondary winding, said primary winding having first and second winding ends; a first amplifier having an input and an output and wherein said input is coupled to said secondary winding for receiving AC electrical voltages therefrom; a loudspEaker for converting AC to audio energy having an input; a microphone having an output; a second amplifier having an input and first and second outputs and wherein said input is coupled to said microphone for receiving electrical voltages therefrom; each of said first and second amplifiers having a DC input for receiving DC power; manually depressible spring return type switch means, said switch means having a normal position and an operated position and having a first set of break contacts and a set of transfer contacts, including a break contact, a make contact, and a transfer contact, and further having a spring for restoring said switch means to said normal position; first circuit means connecting said output of said first amplifier, said first set of break contacts and said loudspeaker in electrical series circuit for permitting coupling of electrical voltages between said amplifier and loudspeaker only when said switch means is in the normal position; second circuit means connecting an output of said second amplifier in circuit with said make contact in said set of transfer contacts whereby said output is connected electrically in circuit with said transfer contact only when said switch means is in the operated position; third electrical circuit means connecting the second output terminal of said second amplifier in common with said first end of said primary winding of said second transformer; fourth circuit means connecting the second end of said primary winding to said break contact of said set of transfer contacts whereby an electrical circuit between said transfer contact and said primary is established only when said switch means is in its normal position; fourth electrical lead means connected between the other contact of said first relay contact set and said transfer contact of said switch transfer contact set; fifth electrical lead means connected between the other contact of said second relay contact set and said first end of said primary winding of said second transformer; sixth electrical lead means connected in circuit between the other contact of said third relay contact set and said DC input of each of said first and second amplifiers; and means controlled by said central station for selectively energizing said relay means.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-08-04 | 1979-02-03 | 1979-08-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-04 | 1983-02-03 | 1983-08-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-04 | 1987-02-03 | 1987-08-05 | $7700.00 | Window Closed / Lapsed |